Comment: A milestone for Crossrail

There is a long saga of false dawns on the 20-year-old Crossrail scheme but today is undoubtedly a historic one for London's east-west link. The Royal Assent to the necessary legislation marks the end of the parliamentary process and a landmark for a desperately needed piece of infrastructure. With London's population forecast to grow by 2025 by an amount equivalent to a city bigger than Leeds, additional public transport is vital.

Recent moves abroad by major firms have highlighted the fact that international business is highly mobile. Transport, as well as the tax and regulatory environment, is a key part of companies' choice of location. Financial and professional services make up nearly a third of London's economy and more than a tenth of the UK's, with a disproportionate contribution to the Exchequer. So a transport system that gets the workforce into the City of London more effectively, as well as enhancing the entire network, is vital for the whole of the British economy.

London will have to brace itself for substantial disruption as the engineering work for a tunnel arguably as ambitious as that under the Channel gets under way. And battles over exactly how the financial demands will fall on the capital's businesses have still to be fought. It is still not clear how any cost over-runs above the £16 billion budget will be borne. But the alternative, allowing inadequate infrastructure to undermine London's success as the world's leading international finance centre, thereby jeopardising one of Britain's principal competitive strengths in the world, should never have been contemplated. Lack of political will, competing priorities and jealousy from other parts of the UK over London's claim to a major public spending commitment have meant that it has taken far longer than it should have done to get to today's milestone. But the UK as a whole should take heart that this landmark has been reached.